The 15 were arrested the day after activists chained themselves together around a plane at Stansted.
Photograph: Chris Radburn/PA

Fifteen people on trial for blocking the takeoff of an immigration removal charter flight from Stansted were acting to protect the human rights of passengers who were at risk of persecution, torture, serious injury or death if they were deported, a court has heard.

At the opening of their defence at Chelmsford crown court on Monday, the defendants began making the case that they had acted out of conscience to protect those on the flight not just from persecution in their destination countries, but also from abuse of process in the UK.

All 15 are on trial for endangering the safety of an aerodrome by chaining themselves together around a Titan Airways flight chartered by the Home Office to remove 60 people to Nigeria, Ghana and Sierra Leone. If convicted, the maximum possible sentence is life in prison.

The court heard they were arrested on 28 March 2017, the day after they walked on to the apron at Stansted, after police spent several hours cutting them free from “lock-on” devices they used to secure themselves around the plane.

The first of the defendants to give evidence, Benjamin Smoke, 27, told the court he had concerns that “hostile environment” immigration policies were leading to the deportation of people who ought to be given asylum to protect their human rights.

Smoke, a freelance journalist and founding member of campaign group Lesbians and Gays Support the Migrants, said he had particular concerns about the safety of deportees who had sought to claim asylum because of their sexuality.

He said he and his co-defendants had learned of the stories of passengers from the Detained Voices blog, which publishes statements from people caught in the UK’s immigration removal process.

“One of them was a woman from Nigeria who … said that she had escaped Nigeria after being in an abusive marriage. She had escaped her abusive ex-husband, her children were living with her sister, [and] she had come to the UK where she was living openly as a lesbian,” Smoke told the court.

“She had put in a claim for asylum on the grounds of her sexuality. It had been refused by the Home Office; she had put in an appeal and she was still waiting for the outcome of that appeal.

“She said that her ex-husband had called her and said something along the lines of: ‘We know you are coming and we are going to kill you when you get here.’”

Asked why he carried out the direct action, Smoke replied: “Because … it was clear that there were people in genuine peril and I felt compelled [to act] and like it was necessary to do something to stop their deaths.”

The prosecution sought to show the activists placed the airport, its staff and passengers at risk. But in his testimony, Smoke said safety had been “integral to every single discussion that had been going on at the time”.

“We were concerned with everyone’s safety; the safety of us, the safety of people due to be deported, the safety of those around the plane,” he told the court.

Safety measures taken by the group included wearing bright-coloured clothing “to make it clear … who we were”, and carrying low-voltage lights “and a big pink banner on the tripod [that they erected behind one of the wings] to make it clear where we were”.

In cross-examination, Tony Badenoch QC, for the prosecution, led Smoke to agree with a series of statements about the rule of law and airport safety. Some supporters in the public gallery stifled a giggle when Badenoch said: “If we all chose our own laws, that would be the world of anarchy, would it not?”

Earlier, the court heard that in statements made after their arrests, the activists told the police they believed the removals were being carried out unlawfully, and that they acted “in a reasonable and proportionate way” to prevent harm coming to those onboard.

Joseph McGahan said he felt anguished after consulting an immigration lawyer who told him many of the people on the flight would have had open applications for asylum or be in the process of appeal.

“My anguish was compounded by their view that this malpractice is currently common and official attempts to restrict it are very often futile, even for professionals,” he said in his statement.

“Hence I concluded that peacefully intercepting and blocking the flight was the only reasonable course of action for an unprofessional person such as myself, and believe that action was proportionate to the threat that was posed.”

On Monday morning, more than 100 supporters of the defendants gathered outside the court. Speakers including former immigration detainees and relatives of the defendants said they believed the defendants were exercising their democratic rights to protest against an unjust immigration regime. The actor Vanessa Redgrave was also present inside the court to show her support for the protesters.

In addition to Smoke and McGahan, May McKeith, Nicholas Sigsworth, Helen Brewer, Lyndsay Burtonshaw, Nathan Clack, Laura Clayson, Mel Evans, Jyotsna Ram, Alistair Temlit, Edward Thacker, Emma Hughes, Ruth Potts and Melanie Stickland are also charged with intentional disruption of services at an aerodrome under the 1990 Aviation and Maritime Security Act, a law passed in response to the 1988 Lockerbie bombing. The defendants, aged 27 to 44, have all pleaded not guilty.